
/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_SLAB_H_INCLUDED_
#define _NGX_SLAB_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


typedef struct ngx_slab_page_s  ngx_slab_page_t;

/*
 *@brief:一个slab内存块的上下文信息;主要是记录了内存块的使用状态信息;
 */
struct ngx_slab_page_s {
    uintptr_t         slab;  //内存块的状态使用标志;
    ngx_slab_page_t  *next;
    uintptr_t         prev;  //uintptr_t 也就是unsigned int 
};


/*
 *@brief: nginx 的slab状态统计信息;
 *
 */
typedef struct {
    ngx_uint_t        total;
    ngx_uint_t        used;

    ngx_uint_t        reqs;
    ngx_uint_t        fails;
} ngx_slab_stat_t;


/*
 *@brief:nginx 对于slab pool的定义
 */
typedef struct {
    ngx_shmtx_sh_t    lock; //

    size_t            min_size;
    size_t            min_shift;  // 3;

    ngx_slab_page_t  *pages;
    ngx_slab_page_t  *last;
    ngx_slab_page_t   free;

    ngx_slab_stat_t  *stats;
    ngx_uint_t        pfree;

    u_char           *start;  //开始位置;
    u_char           *end;  //结束位置;

    ngx_shmtx_t       mutex;  //共享锁;

    u_char           *log_ctx;

	/*****************************************一些标志位**************************************************/
    u_char            zero;
    unsigned          log_nomem:1;
    void             *data;
    void             *addr;

} ngx_slab_pool_t;

/**********************************************************************************************************
 *@d)escription:                                 接口定义
 **********************************************************************************************************/
void ngx_slab_init(ngx_slab_pool_t *pool);
void *ngx_slab_alloc(ngx_slab_pool_t *pool, size_t size);
void *ngx_slab_alloc_locked(ngx_slab_pool_t *pool, size_t size);
void *ngx_slab_calloc(ngx_slab_pool_t *pool, size_t size);
void *ngx_slab_calloc_locked(ngx_slab_pool_t *pool, size_t size);
void ngx_slab_free(ngx_slab_pool_t *pool, void *p);
void ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p);


#endif /* _NGX_SLAB_H_INCLUDED_ */
